1. Field of the Invention
This invention relates to the flat free pneumatic tires having a filling of void free polyurethane elastomer; to such void free polyurethane elastomer per se; to a method of introducing such filling into pneumatic tire casing; and to the reactants for producing such void free polyurethane elastomer.
2. Description of Prior Art
Modern industry demands maximum equipment operating efficiency with a minimum "downtime" of its pneumatic tired machines. In many areas of severe service "downtime" due to the flat tires is a real problem and the many dollars added to the cost of operation cannot be tolerated. Some of these severe operational areas are: aircraft support equipment; dock vehicles; farm equipment; industrial vehicles such as fork lifts and tractors; lumbering operations; mining machinery and vehicles; military vehicles; municipal service equipment; and scrap metal yards. In such severe service areas flat free tires offer a genuine advantage over conventional pneumatic tires or are a necessity.
Automotive vehicles, motor cars and trucks, can use flat free tires on unpaved road or off road service. Vehicles which do not carry spares, such as motorcycles, motor bikes, and bicycles, find flat free tires invaluable.
So-called deflation proof tires have been available for some years; these tires all depend on a foamed elastomer filling. The foamed filling has serious disadvantages, especially excessive heat buildup within the tire during service; filler breakdown during service decreases or eliminates casing support causing severe casing damage. A major disadvantage is the filling must be "factory installed" and this is expensive.
Four patents directed to foamed elastomeric filled tires are cited as of interest in showing the problems of conventional pneumatic tires in severe service and also of foamed fillings: U.S. Pat. No. 3,022,810; 3,112,785; 3,381,735; and 3,605,848.